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Sondo P, Kaboré B, Rouamba T, Compaoré E, Tibiri YNG, Kaboré HAELF, Derra K, Tahita MC, Ilboudo H, Tougri G, Bouda I, Dakyo T, Kafando H, Ouédraogo F, Rouamba E, Hien SVF, Kazienga A, Compaoré CS, Bambara E, Nana M, Dahal P, Garanet F, Kaboré W, Léfèvre T, Guerin P, Tinto H. Enhanced effect of seasonal malaria chemoprevention when coupled with nutrients supplementation for preventing malaria in children under 5 years old in Burkina Faso: a randomized open label trial. Malar J 2023; 22:315. [PMID: 37853408 PMCID: PMC10585892 DOI: 10.1186/s12936-023-04745-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 10/05/2023] [Indexed: 10/20/2023] Open
Abstract
BACKGROUND In rural African settings, most of the children under the coverage of Seasonal Malaria Chemoprevention (SMC) are also undernourished at the time of SMC delivery, justifying the need for packaging malarial and nutritional interventions. This study aimed at assessing the impact of SMC by coupling the intervention with nutrients supplementation for preventing malaria in children less than 5 years old in Burkina Faso. METHODS A randomized trial was carried out between July 2020 and June 2021 in the health district of Nanoro, Burkina Faso. Children (n = 1059) under SMC coverage were randomly assigned to one of the three study arms SMC + Vitamin A (SMC-A, n = 353) or SMC + Vitamin A + Zinc (SMC-AZc, n = 353) or SMC + Vitamin A + PlumpyDoz(tm) (SMC-APd, n = 353)-a medium quantity-lipid-based nutrient supplement (MQ-LNS). Children were followed up for one year that included an active follow-up period of 6 months with scheduled monthly home visits followed by 6 months passive follow-up. At each visit, capillary blood sample was collected for malaria diagnosis by rapid diagnosis test (RDT). RESULTS Adding nutritional supplements to SMC had an effect on the incidence of malaria. A reduction of 23% (adjusted IRR = 0.77 (95%CI 0.61-0.97) in the odds of having uncomplicated malaria in SMC-APd arm but not with SMC-AZc arm adjusted IRR = 0.82 (95%CI 0.65-1.04) compare to control arm was observed. A reduction of 52%, adjusted IRR = 0.48 (95%CI 0.23-0.98) in the odds of having severe malaria was observed in SMC-APd arm compared to control arm. Besides the effect on malaria, this combined strategy had an effect on all-cause morbidity. More specifically, a reduction of morbidity odds of 24%, adjusted IRR = 0.76 (95%CI 0.60-0.94) in SMC-APd arm compared to control arm was observed. Unlike clinical episodes, no effect of nutrient supplementation on cross sectional asymptomatic infections was observed. CONCLUSION Adding nutritional supplements to SMC significantly increases the impact of this intervention for preventing children from malaria and other childhood infections. TRIAL REGISTRATION NCT04238845.
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Affiliation(s)
- Paul Sondo
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso.
| | - Bérenger Kaboré
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Toussaint Rouamba
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Eulalie Compaoré
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | | | | | - Karim Derra
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Marc Christian Tahita
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Hamidou Ilboudo
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Gauthier Tougri
- Ministry of Health of Burkina Faso/Ouagadougou, Ouagadougou, Burkina Faso
| | - Ismaïla Bouda
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Tikanou Dakyo
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Hyacinthe Kafando
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Florence Ouédraogo
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Eli Rouamba
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - So-Vii Franck Hien
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Adama Kazienga
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | | | - Estelle Bambara
- Ministry of Health of Burkina Faso/Ouagadougou, Ouagadougou, Burkina Faso
| | - Macaire Nana
- Ministry of Health of Burkina Faso/Ouagadougou, Ouagadougou, Burkina Faso
| | - Prabin Dahal
- Infectious Diseases Data Observatory (IDDO)-WorldWide Antimalarial Resistance Network (WWARN), Oxford, UK
| | - Franck Garanet
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - William Kaboré
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Thierry Léfèvre
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Université de Montpellier, Institut de Recherche Pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS), Montpellier, France
| | - Philippe Guerin
- Infectious Diseases Data Observatory (IDDO)-WorldWide Antimalarial Resistance Network (WWARN), Oxford, UK
| | - Halidou Tinto
- Institut de Recherche en Sciences de La Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
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Sondo P, Rouamba T, Tahita MC, Derra K, Kabore B, Tibiri YNG, Kabore HAELF, Hien SVF, Ouedraogo F, Kazienga A, Ilboudo H, Rouamba E, Lefevre T, Tinto H. Baseline malarial and nutritional profile of children under seasonal malaria chemoprevention coverage in the health district of Nanoro, Burkina Faso. PLoS One 2023; 18:e0287210. [PMID: 37363896 DOI: 10.1371/journal.pone.0287210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 05/26/2023] [Indexed: 06/28/2023] Open
Abstract
Seasonal Malaria chemoprevention (SMC) is one of the large-scale life-saving malaria interventions initially recommended for the Sahel subregion, including Burkina Faso and recently extended to other parts of Africa. Initially, SMC was restricted to children 3 to 59 months old, but an extension to older children in some locations was recently recommended. Further characterization of SMC population profile beyond age criterion is necessary for understanding factors that could negatively impact the effectiveness of the intervention and to define complementary measures that could enhance its impact. Children were assessed through a cross-sectional survey during the first month of the 2020 SMC campaign (July-August 2020) as part of the SMC-NUT project in the health district of Nanoro. Parameters such as body temperature, weight, height, mid-upper arm circumference (MUAC) were assessed. In addition, blood sample was collected for malaria diagnosis by rapid diagnostic tests (RDT) and microscopy, and for haemoglobin measurement. A total of 1059 children were enrolled. RDT positivity rate (RPR) was 22.2%, while microscopy positivity rate (MPR) was 10.4%, with parasitaemia levels ranging from 40 to 70480/μL. RPR and MPR increased as patient age increased. Wasting was observed in 7.25% of children under SMC coverage while the prevalence of stunting and underweight was 48.79% and 23.38%, respectively. As the age of the children increased, an improvement in their nutritional status was observed. Finally, undernourished children had higher parasite densities than children with adequate nutritional status. In the health district of Nanoro, children who received Seasonal Malaria Chemoprevention (SMC) were mostly undernourished during the period of SMC delivery, suggesting the need for combining the SMC with synergistic interventions against malnutrition to achieve best impact.
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Affiliation(s)
- Paul Sondo
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Toussaint Rouamba
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Marc Christian Tahita
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Karim Derra
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Berenger Kabore
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | | | | | - So-Vii Franck Hien
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Florence Ouedraogo
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Adama Kazienga
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Hamidou Ilboudo
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Eli Rouamba
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
| | - Thiery Lefevre
- Institut de Recherche pour le Développement (IRD), Centre National pour la Recherche Scientifique (CNRS), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Université de Montpellier, Montpellier, France
| | - Halidou Tinto
- Institut de Recherche en Sciences de la Santé (IRSS), Clinical Research Unit of Nanoro (CRUN), Nanoro, Burkina Faso
- Institut de Recherche pour le Développement (IRD), Centre National pour la Recherche Scientifique (CNRS), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Université de Montpellier, Montpellier, France
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Gabain IL, Ramsteijn AS, Webster JP. Parasites and childhood stunting - a mechanistic interplay with nutrition, anaemia, gut health, microbiota, and epigenetics. Trends Parasitol 2023; 39:167-180. [PMID: 36707340 DOI: 10.1016/j.pt.2022.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 12/13/2022] [Accepted: 12/16/2022] [Indexed: 01/26/2023]
Abstract
Globally, stunting affects approximately 149.2 million children under 5 years of age. The underlying aetiology and pathophysiological mechanisms leading to stunting remain elusive, and therefore few effective treatment and prevention strategies exist. Crucial evidence directly linking parasites to stunting is often lacking - in part due to the complex nature of stunting, as well as a lack of critical multidisciplinary research amongst key age groups. Here, based on available studies, we present potential mechanistic pathways by which parasitic infection of mother and/or infant may lead to childhood stunting. We highlight the need for future multidisciplinary longitudinal studies and clinical trials aimed at elucidating the most influential factors, and synergies therein, that can lead to stunting, and ultimately towards finding solutions to successfully mitigate against it.
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Affiliation(s)
- Isobel L Gabain
- Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Herts, AL9 7TA, UK; London Centre for Neglected Tropical Diseases Research, Imperial College London Faculty of Medicine, St Mary's Hospital Campus, London, W2 1NY, UK.
| | | | - Joanne P Webster
- Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Herts, AL9 7TA, UK; London Centre for Neglected Tropical Diseases Research, Imperial College London Faculty of Medicine, St Mary's Hospital Campus, London, W2 1NY, UK
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Cerna-Turoff I, Maurer K, Baiocchi M. Pre-processing data to reduce biases: full matching incorporating an instrumental variable in population-based studies. Int J Epidemiol 2022; 51:1920-1930. [PMID: 35560220 DOI: 10.1093/ije/dyac097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 04/30/2022] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Epidemiologists are often concerned with unobserved biases that produce confounding in population-based studies. We introduce a new design approach-'full matching incorporating an instrumental variable (IV)' or 'Full-IV Matching'-and illustrate its utility in reducing observed and unobserved biases to increase inference accuracy. Our motivating example is tailored to a central question in humanitarian emergencies-the difference in sexual violence risk by displacement setting. METHODS We conducted a series of 1000 Monte Carlo simulations generated from a population-based survey after the 2010 Haitian earthquake and included earthquake damage severity as an IV and the unmeasured variable of 'social capital'. We compared standardized mean differences (SMDs) for covariates after different designs to understand potential biases. Mean risk differences (RDs) were used to assess each design's accuracy in estimating the oracle of the simulated data set. RESULTS Naive analysis and pair matching equivalently performed. Full matching reduced imbalances between exposed and comparison groups across covariates, except for the unobserved covariate of 'social capital'. Pair and full matching overstated differences in sexual violence risk when displaced to a camp vs a community [pair: RD = 0.13, 95% simulation interval (SI) 0.09-0.16; full: RD = 0.11, 95% SI 0.08-0.14). Full-IV Matching reduced imbalances across observed covariates and importantly 'social capital'. The estimated risk difference (RD = 0.07, 95% SI 0.03-0.11) was closest to the oracle (RD = 0.06, 95% SI 0.4-0.8). CONCLUSION Full-IV Matching is a novel approach that is promising for increasing inference accuracy when unmeasured sources of bias likely exist.
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Affiliation(s)
- Ilan Cerna-Turoff
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Katherine Maurer
- School of Social Work, McGill University, Montreal, Québec, Canada
| | - Michael Baiocchi
- Department of Epidemiology and Population Health, Stanford University, Palo Alto, CA, USA
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Smith MR, Gbedande K, Johnson CM, Campbell LA, Onjiko RS, Domingo ND, Opata MM. Model of severe malaria in young mice suggests unique response of CD4 T cells. Parasite Immunol 2022; 44:e12952. [PMID: 36131528 PMCID: PMC9787679 DOI: 10.1111/pim.12952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 12/30/2022]
Abstract
Severe malaria occurs most in young children but is poorly understood due to the absence of a developmentally-equivalent rodent model to study the pathogenesis of the disease. Though functional and quantitative deficiencies in innate response and a biased T helper 1 (Th1) response are reported in newborn pups, there is little information available about this intermediate stage of the adaptive immune system in murine neonates. To fill this gap in knowledge, we have developed a mouse model of severe malaria in young mice using 15-day old mice (pups) infected with Plasmodium chabaudi. We observe similar parasite growth pattern in pups and adults, with a 60% mortality and a decrease in the growth rate of the surviving young mice. Using a battery of behavioral assays, we observed neurological symptoms in pups that do not occur in infected wildtype adults. CD4+ T cells were activated and differentiated to an effector T cell (Teff) phenotype in both adult and pups. However, there were relatively fewer and less terminally differentiated pup CD4+ Teff than adult Teff. Interestingly, despite less activation, the pup Teff expressed higher T-bet than adults' cells. These data suggest that Th1 cells are functional in pups during Plasmodium infection but develop slowly.
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Affiliation(s)
- Margaret R. Smith
- Department of Biology, College of Arts and SciencesAppalachian State UniversityBooneNorth CarolinaUSA,Present address:
Cancer Biology Ph.D. ProgramWake Forest College of MedicineWinston SalemNorth CarolinaUSA
| | - Komi Gbedande
- Division of Infectious Diseases, Department of Internal MedicineUniversity of Texas Medical BranchGalvestonTexasUSA
| | - Corey M. Johnson
- Department of Biology, College of Arts and SciencesAppalachian State UniversityBooneNorth CarolinaUSA
| | - Logan A. Campbell
- Department of Biology, College of Arts and SciencesAppalachian State UniversityBooneNorth CarolinaUSA
| | - Robert S. Onjiko
- Department of Biology, College of Arts and SciencesAppalachian State UniversityBooneNorth CarolinaUSA
| | - Nadia D. Domingo
- Division of Infectious Diseases, Department of Internal MedicineUniversity of Texas Medical BranchGalvestonTexasUSA
| | - Michael M. Opata
- Department of Biology, College of Arts and SciencesAppalachian State UniversityBooneNorth CarolinaUSA
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Hasegawa RB, Small DS. Estimating Malaria Vaccine Efficacy in the Absence of a Gold Standard Case Definition: Mendelian Factorial Design. J Am Stat Assoc 2022. [DOI: 10.1080/01621459.2020.1863222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Raiden B. Hasegawa
- Department of Statistics, The Wharton School, University of Pennsylvania, Philadelphia, PA
| | - Dylan S. Small
- Department of Statistics, The Wharton School, University of Pennsylvania, Philadelphia, PA
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Johnson M, Cao J, Kang H. Detecting heterogeneous treatment effects with instrumental variables and application to the Oregon health insurance experiment. Ann Appl Stat 2022. [DOI: 10.1214/21-aoas1535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
| | - Jiongyi Cao
- Department of Statistics, University of Chicago
| | - Hyunseung Kang
- Department of Statistics, University of Wisconsin-Madison
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The Efficacy of Fish as an Early Complementary Food on the Linear Growth of Infants Aged 6-7 Months: A Randomised Controlled Trial. Nutrients 2022; 14:nu14112191. [PMID: 35683991 PMCID: PMC9182483 DOI: 10.3390/nu14112191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/11/2022] [Accepted: 04/22/2022] [Indexed: 12/04/2022] Open
Abstract
Fish is a good animal-source protein for growth and development. The main objective of the study was to assess the efficacy of fish during the early complementary feeding period on infants’ linear growth in the Samfya district of the Luapula Province of Zambia in 6 months randomised controlled trial. The study was conducted from April 2019 to January 2020. Infants aged 6–7 months (N = 238) were assigned to either the intervention (treatment) group or control (placebo) group to receive fish powder or sorghum powder, respectively. Participants were followed on a weekly basis to distribute the powder and record compliance/usage and any morbidities. Anthropometric measurements were taken monthly. A linear mixed-effects model showed that fish powder improved linear growth among infants over all the 6 months of the intervention period. The fish powder increased length-for-age z scores by 1.26 (95% CI: 0.94–1.57) and weight-for-age z score by 0.95 (95% CI 0.6–1.23). The addition of fish powder to the infant’s usual food during the early complementary feeding improves the infant’s linear growth outcome.
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Mmbando BP, Mwaiswelo RO, Chacky F, Molteni F, Mohamed A, Lazaro S, Ngasala B. Nutritional status of children under five years old involved in a seasonal malaria chemoprevention study in the Nanyumbu and Masasi districts in Tanzania. PLoS One 2022; 17:e0267670. [PMID: 35486649 PMCID: PMC9053822 DOI: 10.1371/journal.pone.0267670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 04/12/2022] [Indexed: 11/25/2022] Open
Abstract
Background Malnutrition and malaria are common co-morbidities in low-income countries, especially among under-fives children. But the malnutrition situation in Masasi and Nanyumbu districts, its interaction with malaria infection and the influence of socioeconomic factors are not well understood. Methods Children aged between 3–59 months in Masasi and Nanyumbu were screened for nutritional status and malaria infection in the community. Nutritional status was determined using age and anthropometric parameters. Z-scores (weight for age (WAZ), height for age (HAZ) and weight for height (WHZ)) were calculated based on the World Health Organisation (WHO) growth reference curves. Malaria infection was determined using malaria rapid diagnostic test and microscopy. Hemoglobin concentration was assessed using HemoCue spectrophotometer, and anemia was classified as hemoglobin concentration < 11.0g/dL. Structured questionnaire was used to collect socio- demographic information electronically. Results A total of 2242 children, 1539 (68.6%) from Masasi and 1169 (52.1%) females were involved in the study. The mean z-scores (WAZ = -0.60 and HAZ = -1.56) were lower than the WHO reference population. The overall prevalence of malnutrition was 49%, and it was significantly higher in Nanyumbu (52.5%) than in Masasi (47.3%), (x2 = 5.045, p = 0.025). Prevalence of malnutrition was higher in boys (53.0%) than in girls (45.0%) (x2 = 13.9, p < 0.001). Stunting was the most prevalent component of undernutrition; it was slightly prevalent in Nanyumbu (46.5%) compared to Masasi (42.0%), (x2 = 3.624, p = 0.057) and in boys (48.2%) than in girls (39.1%), x2 = 17.44, p<0.001. Only 15.8% of the undernourished children had malaria infection. Sex, age group and anaemia were significantly associated with undernourishment (p<0.05), while district and malaria infection were marginally (p≤0.06) associated with undernourishment. None of the undernutrition indices was associated with malaria infection. Conclusion Undernutrition was highly prevalent in the study population and was influenced sex, age, anaemia and malaria infection. More emphasis is needed to address the malnutrition problem especially stunting in Masasi and Nanyumbu districts.
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Affiliation(s)
- Bruno P Mmbando
- National Institute for Medical Research, Tanga Centre, Tanga, Tanzania
| | - Richard O Mwaiswelo
- Department of Microbiology, Immunology and Parasitology, Hubert Kairuki Memorial University, Dar es Salaam, Tanzania
| | - Frank Chacky
- National Malaria Control Programme, Ministry of Health, Dodoma, Tanzania
| | - Fabrizio Molteni
- National Malaria Control Programme, Ministry of Health, Dodoma, Tanzania
| | - Ally Mohamed
- National Malaria Control Programme, Ministry of Health, Dodoma, Tanzania
| | - Samwel Lazaro
- National Malaria Control Programme, Ministry of Health, Dodoma, Tanzania
| | - Billy Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
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Zhang L, Lewsey J, McAlliste DA. Comparative effectiveness research considered methodological insights from simulation studies in physician’s prescribing preference. J Clin Epidemiol 2022; 148:74-80. [DOI: 10.1016/j.jclinepi.2022.04.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 03/06/2022] [Accepted: 04/13/2022] [Indexed: 11/28/2022]
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Abstract
Mendelian randomization (MR) is a method of studying the causal effects of modifiable exposures (i.e., potential risk factors) on health, social, and economic outcomes using genetic variants associated with the specific exposures of interest. MR provides a more robust understanding of the influence of these exposures on outcomes because germline genetic variants are randomly inherited from parents to offspring and, as a result, should not be related to potential confounding factors that influence exposure-outcome associations. The genetic variant can therefore be used as a tool to link the proposed risk factor and outcome, and to estimate this effect with less confounding and bias than conventional epidemiological approaches. We describe the scope of MR, highlighting the range of applications being made possible as genetic data sets and resources become larger and more freely available. We outline the MR approach in detail, covering concepts, assumptions, and estimation methods. We cover some common misconceptions, provide strategies for overcoming violation of assumptions, and discuss future prospects for extending the clinical applicability, methodological innovations, robustness, and generalizability of MR findings.
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Affiliation(s)
- Rebecca C Richmond
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol BS8 2BN, United Kingdom
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol BS8 2BN, United Kingdom
| | - George Davey Smith
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol BS8 2BN, United Kingdom
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol BS8 2BN, United Kingdom
- NIHR Bristol Biomedical Research Centre, University Hospitals Bristol NHS Foundation Trust and University of Bristol, Bristol BS1 3NU, United Kingdom
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Diemer EW, Swanson SA. Diemer and Swanson Reply to "Considerations Before Using Pandemic as Instrument". Am J Epidemiol 2021; 190:2280-2283. [PMID: 34132326 PMCID: PMC8344475 DOI: 10.1093/aje/kwab175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/03/2021] [Accepted: 06/08/2021] [Indexed: 11/28/2022] Open
Abstract
Dimitris and Platt (Am J Epidemiol. 2021;190(11):2275-2279) take on the challenging topic of using "shocks" such as the severe acute respiratory system coronavirus 2 (SARS-CoV-2) pandemic as instrumental variables to study the effect of some exposure on some outcome. Evoking our recent lived experiences, they conclude that the assumptions necessary for an instrumental variable analysis will often be violated and therefore strongly caution against such analyses. Here, we build upon this warranted caution while acknowledging that such analyses will still be pursued and conducted. We discuss strategies for evaluating or reasoning about when such an analysis is clearly inappropriate for a given research question, as well as strategies for interpreting study findings with special attention to incorporating plausible sources of bias in any conclusions drawn from a given finding.
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Affiliation(s)
| | - Sonja A Swanson
- Correspondence to Dr. Sonja A. Swanson, Department of Epidemiology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands (e-mail: )
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Ateba FF, Doumbia S, ter Kuile FO, Terlouw DJ, Lefebvre G, Kariuki S, Small DS. The effect of malaria on stunting: an instrumental variables approach. Trans R Soc Trop Med Hyg 2021; 115:1094-1098. [PMID: 33493346 PMCID: PMC8578805 DOI: 10.1093/trstmh/traa183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 11/05/2020] [Accepted: 12/24/2020] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Previous studies have found mixed evidence for an effect of malaria on stunting, but have suffered from concerns about confounding and/or power. Currently, an effect of malaria on stunting is not included in the Lives Saved Tool (LiST) model. METHODS We used instrumental variables regression with the sickle cell trait and random assignment to bednets as instruments in the analysis of data on children aged 0-2 y from a bednet trial in western Kenya. RESULTS We estimated that one additional clinical malaria episode per year increases the odds of a child being stunted by 6% (OR estimate: 1.06, 95% CI 1.01 to 1.11). CONCLUSIONS Our finding that malaria affects stunting suggests that an effect of malaria on stunting in young children should be considered in the LiST model.
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Affiliation(s)
- François Freddy Ateba
- Malaria Research and Training Center & Department of Public Health Education and Research of the Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technologies of Bamako, BP 1805 Point G Bamako, Mali
- Department of Mathematics, University of Quebec at Montreal (UQAM), Montréal, QC H2X 3Y7, Canada
| | - Seydou Doumbia
- Malaria Research and Training Center & Department of Public Health Education and Research of the Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technologies of Bamako, BP 1805 Point G Bamako, Mali
| | - Feiko O ter Kuile
- Liverpool School of Tropical Medicine, Department of Clinical Sciences, Pembroke Place, Liverpool L3 5QA, UK
- Centre for Global Health Research, Kenya Medical Research Institute (KEMRI), P.O. Box 1578, 40100 Kisumu, Kenya
| | - Dianne J Terlouw
- Liverpool School of Tropical Medicine, Department of Clinical Sciences, Pembroke Place, Liverpool L3 5QA, UK
- Malawi-Liverpool Wellcome Trust Clinical Research Programme (MLW), P.O. Box 30096 Blantyre, Malawi
| | - Genevieve Lefebvre
- Department of Mathematics, University of Quebec at Montreal (UQAM), Montréal, QC H2X 3Y7, Canada
| | - Simon Kariuki
- Centre for Global Health Research, Kenya Medical Research Institute (KEMRI), P.O. Box 1578, 40100 Kisumu, Kenya
| | - Dylan S Small
- Department of Statistics, Wharton School, University of Pennsylvania, 464 Jon M. Huntsman Hall 3730 Walnut Street Philadelphia, PA 19104 Philadelphia, PA, USA
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Branson Z, Keele L. Evaluating a Key Instrumental Variable Assumption Using Randomization Tests. Am J Epidemiol 2020; 189:1412-1420. [PMID: 32432319 DOI: 10.1093/aje/kwaa089] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 05/12/2020] [Accepted: 05/13/2020] [Indexed: 11/14/2022] Open
Abstract
Instrumental variable (IV) analyses are becoming common in health services research and epidemiology. Most IV analyses use naturally occurring instruments, such as distance to a hospital. In these analyses, investigators must assume that the instrument is as-if randomly assigned. This assumption cannot be tested directly, but it can be falsified. Most IV falsification tests compare relative prevalence or bias in observed covariates between the instrument and exposure. These tests require investigators to make covariate-by-covariate judgments about the validity of the IV design. Often, only some covariates are well-balanced, making it unclear whether as-if randomization can be assumed for the instrument. We propose an alternative falsification test that compares IV balance or bias with the balance or bias that would have been produced under randomization. A key advantage of our test is that it allows for global balance measures as well as easily interpretable graphical comparisons. Furthermore, our test does not rely on parametric assumptions and can be used to validly assess whether the instrument is significantly closer to being as-if randomized than the exposure. We demonstrate our approach using data from (SPOT)light, a prospective cohort study carried out in 48 National Health Service hospitals in the United Kingdom between November 1, 2010, and December 31, 2011. This study used bed availability in the intensive care unit as an instrument for admission to the intensive care unit.
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15
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Nwokocha CR, Bafor EE, Ajayi OI, Ebeigbe AB. The Malaria-High Blood Pressure Hypothesis: Revisited. Am J Hypertens 2020; 33:695-702. [PMID: 32211753 DOI: 10.1093/ajh/hpaa051] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 02/24/2020] [Accepted: 03/18/2020] [Indexed: 11/14/2022] Open
Abstract
Malaria etiologies with pathophysiological similarities to hypertension currently constitute a major subject of research. The malaria-high blood pressure hypothesis is strongly supported by observations of the increasing incidence of hypertension in malaria-endemic, low- and middle-income countries with poor socioeconomic conditions, particularly in sub-Saharan African countries. Malnutrition and low birth weight with persistent symptomatic malaria presentations in pregnancy correlate strongly with the development of preeclampsia, gestational hypertension and subsequent hypertension in adult life. Evidence suggest that the link between malaria infection and high blood pressure involves interactions between malaria parasites and erythrocytes, the inflammatory process, effects of the infection during pregnancy; effects on renal and vascular functions as well as effects in sickle cell disease. Possible mechanisms which provide justification for the malaria-high blood pressure hypothesis include the following: endothelial dysfunction (reduced nitric oxide (NO) levels), impaired release of local neurotransmitters and cytokines, decrease in vascular smooth muscle cell viability and/or alterations in cellular calcium signaling leading to enhanced vascular reactivity, remodeling, and cardiomyopathies, deranged homeostasis through dehydration, elevated intracellular mediators and proinflammatory cytokine responses, possible genetic regulations, activation of the renin-angiotensin-aldosterone system mechanisms and renal derangements, severe anemia and hemolysis, renal failure, and end organ damage. Two key mediators of the malaria-high blood pressure association are: endothelial dysfunction (reduced NO) and increased angiotensin-converting enzyme activity/angiotensin II levels. Sickle cell disease is associated with protection against malaria infection and reduced blood pressure. In this review, we present the state of knowledge about the malaria-blood pressure hypothesis and suggest insights for future studies.
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Affiliation(s)
| | - Enitome E Bafor
- Department of Pharmacology and Toxicology, University of Benin, Benin City, Nigeria
| | - Olutayo I Ajayi
- Department of Physiology, College of Medical Sciences, University of Benin, Benin City, Nigeria
| | - Anthony B Ebeigbe
- Department of Physiology, College of Medical Sciences, University of Benin, Benin City, Nigeria
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Epidemiological links between malaria parasitaemia and hypertension: findings from a population-based survey in rural Côte d'Ivoire. J Hypertens 2020; 37:1384-1392. [PMID: 30801386 PMCID: PMC6587219 DOI: 10.1097/hjh.0000000000002071] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Background: Although potential links between malaria parasitaemia and hypertension have been hypothesized, there is paucity of epidemiologic evidence on this link. We investigated in a population-based survey, the association between malaria parasitaemia and hypertension in Ivorian adults. Methods: We estimated the adjusted odds ratios (OR) and 95% confidence intervals (CI) of hypertension in relation to malaria parasitaemia using multinomial regression, in 997 randomly selected adults in the ‘Côte d’Ivoire Dual Burden of Disease Study’ (CoDuBu), in south-central Côte d’Ivoire. We defined malaria parasitaemia as a positive rapid diagnostic test or identification of Plasmodium spp. on microscopy. Using the mean of the last two of three blood pressure (BP) measurements and questionnaire data, we defined hypertension as SBP at least 140 mmHg or DBP at least 90 mmHg or clinician-diagnosed hypertension. Results: Prevalence of malaria parasitaemia and hypertension were 10 and 22%, respectively. Malaria parasitaemia was negatively associated with hypertension in participants with body temperature 36.5 °C or less [OR 0.23 (95% CI 0.06–0.84)]. Contrastingly, microscopic malaria parasitaemia showed positive associations with hypertension in participants with elevated body temperature [>36.5 °C; OR: 2.93 (95% CI 0.94–9.14)]. Participants having microscopic malaria parasitaemia with elevated body temperature had three-fold higher odds of hypertension [OR: 3.37 (95% CI 1.12–10.0)] than malaria parasitaemia-negatives with lower body temperature. Conclusion: Malaria parasitaemia and hypertension are prevalent and seemingly linked comorbidities in African settings. This link may depend on malaria parasitaemia symptomaticity/latency where individuals with more latent/asymptomatic malaria parasitaemia have lower risk of hypertension and those with more acute/symptomatic malaria parasitaemia have a tendency toward higher BP. The cross-sectional nature of the study limited the distinction of short-term BP elevation (interim pathophysiological stress) from hypertension development. Future longitudinal studies considering malaria/hypertension phenotypes and host molecular variations are needed to clarify involved biological mechanisms, toward comorbidity management.
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17
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Brown A, Dike N, Derkyi-Kwarteng L, Abaidoo C. The effect of recurrent malaria infections on bone and cartilage at the distal femoral epiphysis of rats: A histological study. JOURNAL OF CURRENT RESEARCH IN SCIENTIFIC MEDICINE 2020. [DOI: 10.4103/jcrsm.jcrsm_11_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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18
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Falsification Tests for Instrumental Variable Designs With an Application to Tendency to Operate. Med Care 2019; 57:167-171. [PMID: 30520835 DOI: 10.1097/mlr.0000000000001040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Instrumental variable (IV) methods are becoming an increasingly important tool in health services research as they can provide consistent estimates of causal effects in the presence of unobserved confounding. However, investigators must provide justifications that the IV is independent with any unmeasured confounder and its effect on the outcome occurs only through receipt of the exposure. These assumptions, while plausible in some contexts, cannot be verified from the data. METHODS Falsification tests can be applied to provide evidence for the key IV assumptions. A falsification test cannot prove the assumptions hold, but can provide decisive evidence when the assumption fails. We provide a general overview of falsification tests for IV designs. We highlight a falsification test that utilizes a subpopulation of the data where an overwhelming proportion of units are treated or untreated. If the IV assumptions hold, we should find the intention-to-treat effect is zero within these subpopulations. RESULTS We demonstrate the usage of falsification tests for IV designs using an IV known as tendency to operate from health services research. We show that the falsification test provides no evidence against the IV assumptions in this application.
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19
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Keele L, Small D. Instrumental variables: Don't throw the baby out with the bathwater. Health Serv Res 2019; 54:543-546. [PMID: 30859577 DOI: 10.1111/1475-6773.13130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Luke Keele
- University of Pennsylvania, Philadelphia, Pennsylvania
| | - Dylan Small
- University of Pennsylvania, Philadelphia, Pennsylvania
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20
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Seasonal malaria chemoprevention packaged with malnutrition prevention in northern Nigeria: A pragmatic trial (SMAMP study) with nested case-control. PLoS One 2019; 14:e0210692. [PMID: 30682069 PMCID: PMC6347255 DOI: 10.1371/journal.pone.0210692] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/25/2018] [Indexed: 11/19/2022] Open
Abstract
Integrating seasonal malaria chemoprevention (SMC), recommended by the WHO since 2012 to prevent malaria infection, with nutrition interventions may improve health outcomes and operational efficiencies. This study assessed the effects of co-packaging interventions on distribution coverage, nutrition, and clinical malaria outcomes in northern Nigeria. From August to November 2014, community volunteers delivered sulfadoxine-pyrimethamine and amodiaquine (SP-AQ) door-to-door each month to approximately 7,000 children aged 6–24 months in seven wards of Madobi, Kano State, Nigeria. In three of the wards children additionally received a lipid-based nutrient supplement (LNS–medium quantity), Plumpy Doz. Coverage, adherence, and anthropometric outcomes were assessed through baseline, midline, and endline household surveys. A facility-based case-control study was also conducted to estimate impact on clinical malaria outcomes. Coverage of SP-AQ was similar between arms at 89% (n = 2,409 child-months [88–90%]) in the SP-AQ only arm and 90% (n = 1,947 child-months [88–92%]) in the SP-AQ plus LNS arm (p = 0.52). Coverage of LNS was 83% (n = 2,409 child-months [81–84%]). Whilst there were marked changes in anthropometric status between baseline, midline and endline, these were largely accounted for by socioeconomic status and must be interpreted with care due to possible measurement issues, especially length-based indices. Overall nutritional status of our most robust measure, weight-for-age, does appear to have improved by endline, but was similar in the two study arms, suggesting no additional benefit of the LNS. While the odds of clinical malaria among those who received the intended intervention were lower in each study arm compared to children who did not receive interventions (SP-AQ only OR = 0.23 [0.09–0.6]; SP-AQ plus LNS OR = 0.22 [0.09–0.55]), LNS was not shown to have an additional impact. Coverage of SMC was high regardless of integrating LNS delivery into the SMC campaign. Supplementation with LNS did not appear to impact nutritional outcomes, but appeared to enhance the impact of SP-AQ on clinical odds of malaria. These results indicate that combining nutritional interventions with seasonal malaria chemoprevention in high-risk areas can be done successfully, warranting further exploration with other products or dosing. Trial Registration: ISRCTN 11413895
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21
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Agustina R, Dartanto T, Sitompul R, Susiloretni KA, Achadi EL, Taher A, Wirawan F, Sungkar S, Sudarmono P, Shankar AH, Thabrany H. Universal health coverage in Indonesia: concept, progress, and challenges. Lancet 2019; 393:75-102. [PMID: 30579611 DOI: 10.1016/s0140-6736(18)31647-7] [Citation(s) in RCA: 184] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 07/09/2018] [Accepted: 07/12/2018] [Indexed: 11/20/2022]
Abstract
Indonesia is a rapidly growing middle-income country with 262 million inhabitants from more than 300 ethnic and 730 language groups spread over 17 744 islands, and presents unique challenges for health systems and universal health coverage (UHC). From 1960 to 2001, the centralised health system of Indonesia made gains as medical care infrastructure grew from virtually no primary health centres to 20 900 centres. Life expectancy improved from 48 to 69 years, infant mortality decreased from 76 deaths per 1000 livebirths to 23 per 1000, and the total fertility rate decreased from 5·61 to 2·11. However, gains across the country were starkly uneven with major health gaps, such as the stagnant maternal mortality of around 300 deaths per 100 000 livebirths, and minimal change in neonatal mortality. The centralised one size fits all approach did not address the complexity and diversity in population density and dispersion across islands, diets, diseases, local living styles, health beliefs, human development, and community participation. Decentralisation of governance to 354 districts in 2001, and currently 514 districts, further increased health system heterogeneity and exacerbated equity gaps. The novel UHC system introduced in 2014 focused on accommodating diversity with flexible and adaptive implementation features and quick evidence-driven decisions based on changing needs. The UHC system grew rapidly and covers 203 million people, the largest single-payer scheme in the world, and has improved health equity and service access. With early success, challenges have emerged, such as the so-called missing-middle group, a term used to designate the smaller number of people who have enrolled in UHC in wealth quintiles Q2-Q3 than in other quintiles, and the low UHC coverage of children from birth to age 4 years. Moreover, high costs for non-communicable diseases warrant new features for prevention and promotion of healthy lifestyles, and investment in a robust integrated digital health-information system for front-line health workers is crucial for impact and sustainability. This Review describes the innovative UHC initiative of Indonesia along with the future roadmap required to meet sustainable development goals by 2030.
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Affiliation(s)
- Rina Agustina
- Department of Nutrition, Faculty of Medicine, Universitas Indonesia - Dr Cipto Mangunkusumo General Hospital, Jakarta, Indonesia; Human Nutrition Research Centre, Indonesian Medical Education and Research Institute, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia.
| | - Teguh Dartanto
- Department of Economics and Institute for Economic and Social Research (LPEM), Faculty of Economics and Business, Universitas Indonesia, Depok, Indonesia
| | - Ratna Sitompul
- Department of Ophthalmology, Faculty of Medicine, Universitas Indonesia - Dr Cipto Mangunkusumo General Hospital, Jakarta, Indonesia
| | - Kun A Susiloretni
- Department of Nutrition, Semarang Health Polytechnic, Ministry of Health, Semarang, Indonesia
| | - Endang L Achadi
- Human Nutrition Research Centre, Indonesian Medical Education and Research Institute, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia; Department of Nutrition, Faculty of Public Health, Universitas Indonesia, Depok, Indonesia
| | - Akmal Taher
- Ministry of Health, Jakarta, Indonesia; Department of Urology, Faculty of Medicine, Universitas Indonesia - Dr Cipto Mangunkusumo General Hospital, Jakarta, Indonesia
| | - Fadila Wirawan
- Human Nutrition Research Centre, Indonesian Medical Education and Research Institute, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
| | - Saleha Sungkar
- Department of Parasitology, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
| | - Pratiwi Sudarmono
- Department of Microbiology, Faculty of Medicine, Universitas Indonesia - Dr Cipto Mangunkusumo General Hospital, Jakarta, Indonesia
| | - Anuraj H Shankar
- Human Nutrition Research Centre, Indonesian Medical Education and Research Institute, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia; Department of Nutrition, Harvard TH Chan School of Public Health, Boston, MA, USA
| | - Hasbullah Thabrany
- National Social Security Council and Department of Health Policy and Administration, Universitas Indonesia, Depok, Indonesia
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22
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Bendabenda J, Patson N, Hallamaa L, Mbotwa J, Mangani C, Phuka J, Prado EL, Cheung YB, Ashorn U, Dewey KG, Ashorn P, Maleta K. The association of malaria morbidity with linear growth, hemoglobin, iron status, and development in young Malawian children: a prospective cohort study. BMC Pediatr 2018; 18:396. [PMID: 30593271 PMCID: PMC6309082 DOI: 10.1186/s12887-018-1378-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 12/20/2018] [Indexed: 11/20/2022] Open
Abstract
Background Although poor complementary feeding is associated with poor child growth, nutrition interventions only have modest impact on child growth, due to high burden of infections. We aimed to assess the association of malaria with linear growth, hemoglobin, iron status, and development in children aged 6–18 months in a setting of high malaria and undernutrition prevalence. Methods Prospective cohort study, conducted in Mangochi district, Malawi. We enrolled six-months-old infants and collected weekly data for ‘presumed’ malaria, diarrhea, and acute respiratory infections (ARI) until age 18 months. Change in length-for-age z-scores (LAZ), stunting, hemoglobin, iron status, and development were assessed at age 18 months. We used ordinary least squares regression for continuous outcomes and modified Poisson regression for categorical outcomes. Results Of the 2723 children enrolled, 2016 (74.0%) had complete measurements. The mean (standard deviation) incidences of ‘presumed’ malaria, diarrhea, and ARI, respectively were: 1.4 (2.0), 4.6 (10.1), and 8.3 (5.0) episodes/child year. Prevalence of stunting increased from 27.4 to 41.5% from 6 to 18 months. ‘Presumed’ malaria incidence was associated with higher risk of stunting (risk ratio [RR] = 1.04, 95% confidence interval [CI] = 1.01 to 1.07, p = 0.023), anemia (RR = 1.02, 95%CI = 1.00 to 1.04, p = 0.014) and better socio-emotional scores (B = − 0.21, 95%CI = − 0.39 to − 0.03, p = 0.041), but not with change in LAZ, haemoglobin, iron status or other developmental outcomes. Diarrhea incidence was associated with change in LAZ (B = − 0.02; 95% CI = − 0.03 to − 0.01; p = 0.009), stunting (RR = 1.02; 95% CI = 1.01 to 1.03; p = 0.005), and slower motor development. ARI incidence was not associated with any outcome except for poorer socio-emotional scores. Conclusion In this population of young children living in a malaria-endemic setting, with active surveillance and treatment, ‘presumed’ malaria is not associated with change in LAZ, hemoglobin, or iron status, but could be associated with stunting and anemia. Diarrhea was more consistently associated with growth than was malaria or ARI. The findings may be different in contexts where active malaria surveillance and treatment is not provided. Trial registration NCT00945698 (July 24, 2009) and NCT01239693 (November 11, 2010).
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Affiliation(s)
- Jaden Bendabenda
- College of Medicine, Department of Public Health, School of Public Health, University of Malawi, Mahatma Gandhi Road, Private Bag 360, Blantyre 3, Malawi. .,Faculty of Medicine and Life Sciences, Center for Child Health Research, University of Tampere, Tampere, Finland.
| | - Noel Patson
- College of Medicine, Department of Public Health, School of Public Health, University of Malawi, Mahatma Gandhi Road, Private Bag 360, Blantyre 3, Malawi.,School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Lotta Hallamaa
- Faculty of Medicine and Life Sciences, Center for Child Health Research, University of Tampere, Tampere, Finland
| | - John Mbotwa
- Department of Applied Studies, Malawi University of Science and Technology, Thyolo, Malawi.,Leeds Institute for Data Analytics, University of Leeds, Leeds, UK
| | - Charles Mangani
- College of Medicine, Department of Public Health, School of Public Health, University of Malawi, Mahatma Gandhi Road, Private Bag 360, Blantyre 3, Malawi
| | - John Phuka
- College of Medicine, Department of Public Health, School of Public Health, University of Malawi, Mahatma Gandhi Road, Private Bag 360, Blantyre 3, Malawi
| | - Elizabeth L Prado
- Department of Nutrition, University of California, Davis, Davis, CA, USA
| | - Yin Bun Cheung
- Program in Health Services and Systems Research and Centre for Quantitative Medicine, Duke-National University of Singapore Graduate Medical School, Singapore, Singapore
| | - Ulla Ashorn
- Faculty of Medicine and Life Sciences, Center for Child Health Research, University of Tampere, Tampere, Finland
| | - Kathryn G Dewey
- Department of Nutrition, University of California, Davis, Davis, CA, USA
| | - Per Ashorn
- Faculty of Medicine and Life Sciences, Center for Child Health Research, University of Tampere, Tampere, Finland
| | - Kenneth Maleta
- College of Medicine, Department of Public Health, School of Public Health, University of Malawi, Mahatma Gandhi Road, Private Bag 360, Blantyre 3, Malawi
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Oldenburg CE, Guerin PJ, Berthé F, Grais RF, Isanaka S. Malaria and Nutritional Status Among Children With Severe Acute Malnutrition in Niger: A Prospective Cohort Study. Clin Infect Dis 2018; 67:1027-1034. [PMID: 29522089 PMCID: PMC6137121 DOI: 10.1093/cid/ciy207] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/06/2018] [Indexed: 11/14/2022] Open
Abstract
Background The relationship between malaria infection and nutritional status is complex. Previous studies suggest malaria may increase the incidence and severity of malnutrition, while malnutrition may increase the risk of malaria infection. Here, we report bidirectional associations between malaria and nutritional status among children with uncomplicated severe acute malnutrition (SAM). Methods This study is a secondary analysis of a randomized, controlled trial for the treatment of uncomplicated SAM in Niger. Children aged 6-59 months were enrolled and followed for 12 weeks. Malaria infection was assessed using an histidine-rich protein 2 (HRP2) rapid diagnostic test at admission and at any follow-up visit with fever. We assessed the association of nutritional status at admission on malaria incidence using Cox proportional hazards regression and malaria infection at admission on nutritional recovery and weight and height gain using linear regression. Results Of 2399 children included in the analysis, 1327 (55.3%) were infected with malaria at admission. Malaria incidence was 12.1 cases/100 person-months among those without malaria infection at admission. Nutritional status at admission was not associated with malaria incidence. Children with malaria infection at admission and subsequently treated with an artemisinin-based combination therapy had increased weight gain (0.38 g/kg/day; 95% confidence interval [CI], 0.07 to 0.69) and reduced height gain (-0.002 mm/day; 95% CI, -0.004 to -0.0008). Conclusions Malaria infection was common among children treated for uncomplicated SAM. Malaria infection may impair height gain. Proper medical and nutritional management should be ensured to prevent adverse effects of malaria infection. Clinical Trials Registration NCT01613547.
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Affiliation(s)
- Catherine E Oldenburg
- Francis I. Proctor Foundation, University of California, San Francisco
- Department of Ophthalmology, University of California, San Francisco
| | - Philippe J Guerin
- WorldWide Antimalarial Resistance Network, University of Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | | | | | - Sheila Isanaka
- Department of Research, Epicentre, Paris, France
- Departments of Nutrition and Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
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24
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Wilson AL, Bradley J, Kandeh B, Salami K, D'Alessandro U, Pinder M, Lindsay SW. Is chronic malnutrition associated with an increase in malaria incidence? A cohort study in children aged under 5 years in rural Gambia. Parasit Vectors 2018; 11:451. [PMID: 30081945 PMCID: PMC6090805 DOI: 10.1186/s13071-018-3026-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 07/19/2018] [Indexed: 11/10/2022] Open
Abstract
Background Malnutrition is common in children in sub-Saharan Africa and is thought to increase the risk of infectious diseases, including malaria. The relationship between malnutrition and malaria was examined in a cohort of 6–59 month-old children in rural Gambia, in an area of seasonal malaria transmission. The study used data from a clinical trial in which a cohort of children was established and followed for clinical malaria during the 2011 transmission season. A cross-sectional survey to determine the prevalence of malaria and anaemia, and measure the height and weight of these children was carried out at the beginning and end of the transmission season. Standard anthropometric indices (stunting, wasting and underweight) were calculated using z-scores. Results At the beginning of the transmission season, 31.7% of children were stunted, 10.8% wasted and 24.8% underweight. Stunting was more common in Fula children than other ethnicities and in children from traditionally constructed houses compared to more modern houses. Stunted children and underweight children were significantly more likely to have mild or moderate anaemia. During the transmission season, 13.7% of children had at least one episode of clinical malaria. There was no association between stunting and malaria incidence (odds ratio = 0.79, 95% CI: 0.60–1.05). Malaria was not associated with differences in weight or height gain. Conclusions Chronic malnutrition remains a problem in rural Gambia, particularly among the poor and Fula ethnic group, but it was not associated with an increased risk of malaria. Trial registration Trial registration: ISRCTN, ISRCTN01738840, registered: 27/08/2010 (Retrospectively registered).
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Affiliation(s)
- Anne L Wilson
- Department of Biosciences, Durham University, Stockton Road, Durham, DH1 3LE, UK.
| | - John Bradley
- Medical Research Council Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Ballah Kandeh
- National Malaria Control Programme, Banjul, The Gambia
| | - Kolawole Salami
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia.,Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Margaret Pinder
- Department of Biosciences, Durham University, Stockton Road, Durham, DH1 3LE, UK.,Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Steven W Lindsay
- Department of Biosciences, Durham University, Stockton Road, Durham, DH1 3LE, UK.,Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
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Labrecque J, Swanson SA. Understanding the Assumptions Underlying Instrumental Variable Analyses: a Brief Review of Falsification Strategies and Related Tools. CURR EPIDEMIOL REP 2018; 5:214-220. [PMID: 30148040 PMCID: PMC6096851 DOI: 10.1007/s40471-018-0152-1] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW Instrumental variable (IV) methods continue to be applied to questions ranging from genetic to social epidemiology. In the epidemiologic literature, discussion of whether the assumptions underlying IV analyses hold is often limited to only certain assumptions and even then, arguments are mostly made using subject matter knowledge. To complement subject matter knowledge, there exist a variety of falsification strategies and other tools for weighing the plausibility of the assumptions underlying IV analyses. RECENT FINDINGS There are many tools that can refute the IV assumptions or help estimate the magnitude or direction of possible bias if the conditions do not hold perfectly. Many of these tools, including both recently developed strategies and strategies described decades ago, are underused or only used in specific applications of IV methods in epidemiology. SUMMARY Although estimating causal effects with IV analyses relies on unverifiable assumptions, the assumptions can sometimes be refuted. We suggest that the epidemiologists using IV analyses employ all the falsification strategies that apply to their research question in order to avoid settings that demonstrably violate a core condition for valid inference.
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Affiliation(s)
- Jeremy Labrecque
- Department of Epidemiology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Sonja A. Swanson
- Department of Epidemiology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
- Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA USA
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Amoah B, Giorgi E, Heyes DJ, van Burren S, Diggle PJ. Geostatistical modelling of the association between malaria and child growth in Africa. Int J Health Geogr 2018; 17:7. [PMID: 29482559 PMCID: PMC5828493 DOI: 10.1186/s12942-018-0127-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 02/20/2018] [Indexed: 11/11/2022] Open
Abstract
Background Undernutrition among children under 5 years of age continues to be a public health challenge in many low- and middle-income countries and can lead to growth stunting. Infectious diseases may also affect child growth, however their actual impact on the latter can be difficult to quantify. In this paper, we analyse data from 20 Demographic and Health Surveys (DHS) conducted in 13 African countries to investigate the relationship between malaria and stunting. Our objective is to make inference on the association between malaria incidence during the first year of life and height-for-age Z-scores (HAZs). Methods We develop a geostatistical model for HAZs as a function of both measured and unmeasured child-specific and spatial risk factors. We visualize stunting risk in each of the 20 analysed surveys by mapping the predictive probability that HAZ is below − 2. Finally, we carry out a meta-analysis by modelling the estimated effects of malaria incidence on HAZ from each DHS as a linear regression on national development indicators from the World Bank. Results A non-spatial univariate linear regression of HAZ on malaria incidence showed a negative association in 18 out of 20 surveys. However, after adjusting for spatial risk factors and controlling for confounding effects, we found a weaker association between HAZ and malaria, with a mix of positive and negative estimates, of which 3 out of 20 are significantly different from zero at the conventional 5% level. The meta-analysis showed that this variation in the estimated effect of malaria incidence on HAZ is significantly associated with the amount of arable land. Conclusion Confounding effects on the association between malaria and stunting vary both by country and over time. Geostatistical analysis provides a useful framework that allows to account for unmeasured spatial confounders. Establishing whether the association between malaria and stunting is causal would require longitudinal follow-up data on individual children. Electronic supplementary material The online version of this article (10.1186/s12942-018-0127-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Benjamin Amoah
- CHICAS Research Group, Lancaster Medical School, Lancaster University, Bailrigg, Lancaster, UK
| | - Emanuele Giorgi
- CHICAS Research Group, Lancaster Medical School, Lancaster University, Bailrigg, Lancaster, UK.
| | - Daniel J Heyes
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Stef van Burren
- Department of Child Health, Netherlands Organization for Applied Scientific Research TNO, Leiden, The Netherlands.,Department of Methodology and Statistics, Utrecht University, Utrecht, The Netherlands
| | - Peter John Diggle
- CHICAS Research Group, Lancaster Medical School, Lancaster University, Bailrigg, Lancaster, UK
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Sensitivity Analyses for Robust Causal Inference from Mendelian Randomization Analyses with Multiple Genetic Variants. Epidemiology 2018; 28:30-42. [PMID: 27749700 PMCID: PMC5133381 DOI: 10.1097/ede.0000000000000559] [Citation(s) in RCA: 792] [Impact Index Per Article: 132.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mendelian randomization investigations are becoming more powerful and simpler to perform, due to the increasing size and coverage of genome-wide association studies and the increasing availability of summarized data on genetic associations with risk factors and disease outcomes. However, when using multiple genetic variants from different gene regions in a Mendelian randomization analysis, it is highly implausible that all the genetic variants satisfy the instrumental variable assumptions. This means that a simple instrumental variable analysis alone should not be relied on to give a causal conclusion. In this article, we discuss a range of sensitivity analyses that will either support or question the validity of causal inference from a Mendelian randomization analysis with multiple genetic variants. We focus on sensitivity analyses of greatest practical relevance for ensuring robust causal inferences, and those that can be undertaken using summarized data. Aside from cases in which the justification of the instrumental variable assumptions is supported by strong biological understanding, a Mendelian randomization analysis in which no assessment of the robustness of the findings to violations of the instrumental variable assumptions has been made should be viewed as speculative and incomplete. In particular, Mendelian randomization investigations with large numbers of genetic variants without such sensitivity analyses should be treated with skepticism.
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28
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Jackson BD, Black RE. A Literature Review of the Effect of Malaria on Stunting. J Nutr 2017; 147:2163S-2168S. [PMID: 28904111 DOI: 10.3945/jn.116.242289] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/30/2016] [Accepted: 05/15/2017] [Indexed: 11/14/2022] Open
Abstract
Background: The current version of the Lives Saved Tool (LiST) maternal and child health impact modeling software does not include an effect of malaria on stunting.Objective: This literature review was undertaken to determine whether such a causal link should be included in the LiST model.Methods: The PubMed, Embase, and Scopus databases were searched by using broad search terms. The searches returned a total of 4281 documents. Twelve studies from among the retrieved documents were included in the review according to the inclusion and exclusion criteria.Results: There was mixed evidence for an effect of malaria on stunting among longitudinal observational studies, and none of the randomized controlled trials of malaria interventions found an effect of the interventions on stunting.Conclusions: There is insufficient evidence to include malaria as a determinant of stunting or an effect of malaria interventions on stunting in the LiST model. The paucity and heterogeneity of the available literature were a major limitation. In addition, the studies included in the review consistently fulfilled their ethical responsibility to treat children under observation for malaria, which may have interfered with the natural history of the disease and prevented any observable effect on stunting or linear growth.
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Affiliation(s)
- Bianca D Jackson
- Johns Hopkins Bloomberg School of Public Health, Department of International Health, Institute for International Programs, Baltimore, MD
| | - Robert E Black
- Johns Hopkins Bloomberg School of Public Health, Department of International Health, Institute for International Programs, Baltimore, MD
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Legason ID, Pfeiffer RM, Udquim KI, Bergen AW, Gouveia MH, Kirimunda S, Otim I, Karlins E, Kerchan P, Nabalende H, Bayanjargal A, Emmanuel B, Kagwa P, Talisuna AO, Bhatia K, Yeager M, Biggar RJ, Ayers LW, Reynolds SJ, Goedert JJ, Ogwang MD, Fraumeni JF, Prokunina-Olsson L, Mbulaiteye SM. Evaluating the Causal Link Between Malaria Infection and Endemic Burkitt Lymphoma in Northern Uganda: A Mendelian Randomization Study. EBioMedicine 2017; 25:58-65. [PMID: 29033373 PMCID: PMC5704046 DOI: 10.1016/j.ebiom.2017.09.037] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Revised: 09/16/2017] [Accepted: 09/28/2017] [Indexed: 12/31/2022] Open
Abstract
Background Plasmodium falciparum (Pf) malaria infection is suspected to cause endemic Burkitt Lymphoma (eBL), but the evidence remains unsettled. An inverse relationship between sickle cell trait (SCT) and eBL, which supports that between malaria and eBL, has been reported before, but in small studies with low power. We investigated this hypothesis in children in a population-based study in northern Uganda using Mendelian Randomization. Methods Malaria-related polymorphisms (SCT, IL10, IL1A, CD36, SEMA3C, and IFNAR1) were genotyped in 202 eBL cases and 624 controls enrolled during 2010–2015. We modeled associations between genotypes and eBL or malaria using logistic regression. Findings SCT was associated with decreased risk of eBL (adjusted odds ratio [OR] 0·37, 95% CI 0·21–0·66; p = 0·0003). Decreased risk of eBL was associated with IL10 rs1800896-CT (OR 0·73, 95% CI 0·50–1·07) and -CC genotypes (OR 0·53, 95% CI 0·29–0·95, ptrend = 0·019); IL1A rs2856838-AG (OR 0·56, 95% CI 0·39–0·81) and -AA genotype (OR 0·50, 95% CI 0·28–1·01, ptrend = 0·0016); and SEMA3C rs4461841-CT or -CC genotypes (OR 0·57, 95% CI 0·35–0·93, p = 0·0193). SCT and IL10 rs1800896, IL1A rs2856838, but not SEMA3C rs4461841, polymorphisms were associated with decreased risk of malaria in the controls. Interpretation Our results support a causal effect of malaria infection on eBL. Mendelian randomization analysis was done to assess a causal relationship between malaria infection and endemic Burkitt lymphoma in Uganda Carriage of the sickle cell trait was associated with decreased risk of endemic Burkitt lymphoma Heterozygous or homozygous minor alleles of IL10 rs1800896, IL1A rs2856838, and SEMA3C rs4461841 were associated with decreased risk of endemic Burkitt lymphoma The inverse association between sickle cell trait and endemic Burkitt lymphoma supports a causal role of malaria in endemic Burkitt lymphoma
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Affiliation(s)
- Ismail D Legason
- EMBLEM Study, African Field Epidemiology Network, P.O. Box 12874, Kampala, Uganda
| | - Ruth M Pfeiffer
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Ctr Dr, Bethesda 20892, MD, USA.
| | - Krizia-Ivana Udquim
- Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Andrew W Bergen
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Ctr Dr, Bethesda 20892, MD, USA
| | - Mateus H Gouveia
- Instituto de Pesquisa Rene Rachou, Fundação Oswaldo Cruz, 30190-002 Belo Horizonte, Minas Gerais, Brazil
| | - Samuel Kirimunda
- Department of Medical Microbiology, College of Health Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda
| | - Isaac Otim
- EMBLEM Study, African Field Epidemiology Network, P.O. Box 12874, Kampala, Uganda
| | - Eric Karlins
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Ctr Dr, Bethesda 20892, MD, USA.
| | - Patrick Kerchan
- EMBLEM Study, African Field Epidemiology Network, P.O. Box 12874, Kampala, Uganda
| | - Hadijah Nabalende
- EMBLEM Study, African Field Epidemiology Network, P.O. Box 12874, Kampala, Uganda
| | - Ariunaa Bayanjargal
- Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Benjamin Emmanuel
- EMBLEM Study, African Field Epidemiology Network, P.O. Box 12874, Kampala, Uganda; Benjamin Emmanuel, Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Paul Kagwa
- EMBLEM Study, African Field Epidemiology Network, P.O. Box 12874, Kampala, Uganda
| | - Ambrose O Talisuna
- World Health Organization, Regional Office for Africa, Brazzaville, Congo
| | - Kishor Bhatia
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Ctr Dr, Bethesda 20892, MD, USA.
| | - Meredith Yeager
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Ctr Dr, Bethesda 20892, MD, USA.
| | - Robert J Biggar
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Ctr Dr, Bethesda 20892, MD, USA
| | - Leona W Ayers
- Department of Pathology, The Ohio State University, Columbus, OH, USA.
| | - Steven J Reynolds
- Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
| | - James J Goedert
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Ctr Dr, Bethesda 20892, MD, USA
| | - Martin D Ogwang
- EMBLEM Study, St. Mary's Hospital, Lacor, P.O. Box 180, Gulu, Uganda.
| | - Joseph F Fraumeni
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Ctr Dr, Bethesda 20892, MD, USA.
| | - Ludmila Prokunina-Olsson
- Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Sam M Mbulaiteye
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Ctr Dr, Bethesda 20892, MD, USA.
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30
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Croke K, Ishengoma DS, Francis F, Makani J, Kamugisha ML, Lusingu J, Lemnge M, Larreguy H, Fink G, Mmbando BP. Relationships between sickle cell trait, malaria, and educational outcomes in Tanzania. BMC Infect Dis 2017; 17:568. [PMID: 28810839 PMCID: PMC5558763 DOI: 10.1186/s12879-017-2644-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 07/26/2017] [Indexed: 11/10/2022] Open
Abstract
Background Sickle Cell Trait (SCT) has been shown to be protective against malaria. A growing literature suggests that malaria exposure can reduce educational attainment. This study assessed the relationship and interactions between malaria, SCT and educational attainment in north-eastern Tanzania. Methods Seven hundred sixty seven children were selected from a list of individuals screened for SCT. Febrile illness and malaria incidence were monitored from January 2006 to December 2013 by community health workers. Education outcomes were extracted from the Korogwe Health and Demographic Surveillance system in 2015. The primary independent variables were malaria and SCT. The association between SCT and the number of fever and malaria episodes from 2006 to 2013 was analyzed. Main outcomes of interest were school enrolment and educational attainment in 2015. Results SCT was not associated with school enrolment (adjusted OR 1.42, 95% CI [0.593,3.412]) or highest grade attained (adjusted grade difference 0.0597, 95% CI [−0.567, 0.686]). SCT was associated with a 29% reduction in malaria incidence (adjusted IRR 0.71, 95% CI [0.526, 0.959]) but not with fever incidence (adjusted IRR 0.905, 95% CI [0.709-1.154]). In subgroup analysis of individuals with SCT, malaria exposure was associated with reduced school enrollment (adjusted OR 0.431, 95% CI [0.212, 0.877]). Conclusions SCT appears to reduce incidence of malaria. Overall, children with SCT do not appear to attend more years of school; however children who get malaria despite SCT appear to have lower levels of enrolment in education than their peers.
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Affiliation(s)
- Kevin Croke
- Harvard T. H. Chan School of Public Health, Boston, USA.
| | - Deus S Ishengoma
- National Institute of Medical Research, Tanga Research Centre, Tanga, Tanzania
| | - Filbert Francis
- National Institute of Medical Research, Tanga Research Centre, Tanga, Tanzania
| | - Julie Makani
- Department of Haematology and Blood Transfusion, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Mathias L Kamugisha
- National Institute of Medical Research, Tanga Research Centre, Tanga, Tanzania
| | - John Lusingu
- National Institute of Medical Research, Tanga Research Centre, Tanga, Tanzania
| | - Martha Lemnge
- National Institute of Medical Research, Tanga Research Centre, Tanga, Tanzania
| | | | - Günther Fink
- Harvard T. H. Chan School of Public Health, Boston, USA
| | - Bruno P Mmbando
- National Institute of Medical Research, Tanga Research Centre, Tanga, Tanzania
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31
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Hess SY, Peerson JM, Becquey E, Abbeddou S, Ouédraogo CT, Somé JW, Yakes Jimenez E, Ouédraogo JB, Vosti SA, Rouamba N, Brown KH. Differing growth responses to nutritional supplements in neighboring health districts of Burkina Faso are likely due to benefits of small-quantity lipid-based nutrient supplements (LNS). PLoS One 2017; 12:e0181770. [PMID: 28771493 PMCID: PMC5542440 DOI: 10.1371/journal.pone.0181770] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/28/2017] [Indexed: 12/18/2022] Open
Abstract
Background Of two community-based trials among young children in neighboring health districts of Burkina Faso, one found that small-quantity lipid-based nutrient supplements (LNS) increased child growth compared with a non-intervention control group, but zinc supplementation did not in the second study. Objectives We explored whether the disparate growth outcomes were associated with differences in intervention components, household demographic variables, and/or children’s morbidity. Methods Children in the LNS study received 20g LNS daily containing different amounts of zinc (LNS). Children in the zinc supplementation study received different zinc supplementation regimens (Z-Suppl). Children in both studies were visited weekly for morbidity surveillance. Free malaria and diarrhea treatment was provided by the field worker in the LNS study, and by a village-based community-health worker in the zinc study. Anthropometric assessments were repeated every 13–16 weeks. For the present analyses, study intervals of the two studies were matched by child age and month of enrollment. The changes in length-for-age z-score (LAZ) per interval were compared between LNS and Z-Suppl groups using mixed model ANOVA or ANCOVA. Covariates were added to the model in blocks, and adjusted differences between group means were estimated. Results Mean ages at enrollment of LNS (n = 1716) and Z-Suppl (n = 1720) were 9.4±0.4 and 10.1±2.7 months, respectively. The age-adjusted change in mean LAZ per interval declined less with LNS (-0.07±0.44) versus Z-Suppl (-0.21±0.43; p<0.0001). There was a significant group by interval interaction with the greatest difference found in 9–12 month old children (p<0.0001). Adjusting for demographic characteristics and morbidity did not reduce the observed differences by type of intervention, even though the morbidity burden was greater in the LNS group. Conclusions Greater average physical growth in children who received LNS could not be explained by known cross-trial differences in baseline characteristics or morbidity burden, implying that the observed difference in growth response was partly due to LNS.
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Affiliation(s)
- Sonja Y. Hess
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
- * E-mail:
| | - Janet M. Peerson
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
| | - Elodie Becquey
- Poverty, Health and Nutrition Division, International Food Policy Research Institute, Washington, DC, United States of America
| | - Souheila Abbeddou
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
| | - Césaire T. Ouédraogo
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
- Direction Régionale de l'Ouest, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Jérôme W. Somé
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
- Direction Régionale de l'Ouest, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Elizabeth Yakes Jimenez
- Center for Education Policy Research and Division of Epidemiology, Biostatistics and Preventive Medicine, Department of Internal Medicine, University of New Mexico, Albuquerque, NM, United States of America
| | - Jean-Bosco Ouédraogo
- Direction Régionale de l'Ouest, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Stephen A. Vosti
- Department of Agricultural and Resource Economics, University of California, Davis, Davis, CA, United States of America
| | - Noël Rouamba
- Direction Régionale de l'Ouest, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Kenneth H. Brown
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
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Mosites E, Dawson-Hahn E, Walson J, Rowhani-Rahbar A, Neuhouser ML. Piecing together the stunting puzzle: a framework for attributable factors of child stunting. Paediatr Int Child Health 2017; 37:158-165. [PMID: 27680199 DOI: 10.1080/20469047.2016.1230952] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Reducing the burden of stunting in childhood is critical to improving health in low- and middle-income settings. However, because many aetiologies underlie linear growth failure, stunting has proved difficult to prevent and reverse. Understanding the contributions these aetiologies make to the burden of stunting can help the development of targeted, effective interventions. To begin to frame these causes, a qualitative and a quantitative framework of the primary drivers of stunting in low-resource settings were developed. Population attributable fractions (PAF) were estimated to inform the quantitative framework. According to these estimates, infectious diseases were responsible for large attributable fractions in all settings, and a combination of dietary indicators also comprised a large fraction in Africa. However, the PAF calculation was found to have several limitations, including a requirement for a binary outcome and sensitivity to confounding, which necessitate broad interpretation of the results. More robust tools to model complex causality are needed in order to understand the causal aetiology of stunting.
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Affiliation(s)
- Emily Mosites
- a Department of Epidemiology , University of Washington , Seattle , USA.,b Paul G. Allen School for Global Animal Health , Washington State University , Pullman , USA
| | | | - Judd Walson
- a Department of Epidemiology , University of Washington , Seattle , USA.,c Department of Pediatrics , University of Washington , Seattle , USA.,d Department of Global Health , University of Washington , Seattle , USA.,e Department of Allergy and Infectious Disease , University of Washington , Seattle , USA
| | | | - Marian L Neuhouser
- a Department of Epidemiology , University of Washington , Seattle , USA.,f Division of Public Health Sciences , Fred Hutchinson Cancer Research Center , Seattle , USA
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Lee MSJ, Maruyama K, Fujita Y, Konishi A, Lelliott PM, Itagaki S, Horii T, Lin JW, Khan SM, Kuroda E, Akira S, Ishii KJ, Coban C. Plasmodium products persist in the bone marrow and promote chronic bone loss. Sci Immunol 2017; 2:2/12/eaam8093. [PMID: 28783657 DOI: 10.1126/sciimmunol.aam8093] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/28/2017] [Indexed: 12/18/2022]
Abstract
Although malaria is a life-threatening disease with severe complications, most people develop partial immunity and suffer from mild symptoms. However, incomplete recovery from infection causes chronic illness, and little is known of the potential outcomes of this chronicity. We found that malaria causes bone loss and growth retardation as a result of chronic bone inflammation induced by Plasmodium products. Acute malaria infection severely suppresses bone homeostasis, but sustained accumulation of Plasmodium products in the bone marrow niche induces MyD88-dependent inflammatory responses in osteoclast and osteoblast precursors, leading to increased RANKL expression and overstimulation of osteoclastogenesis, favoring bone resorption. Infection with a mutant parasite with impaired hemoglobin digestion that produces little hemozoin, a major Plasmodium by-product, did not cause bone loss. Supplementation of alfacalcidol, a vitamin D3 analog, could prevent the bone loss. These results highlight the risk of bone loss in malaria-infected patients and the potential benefits of coupling bone therapy with antimalarial treatment.
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Affiliation(s)
- Michelle S J Lee
- Laboratory of Malaria Immunology, Immunology Frontier Research Center (IFReC), Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Kenta Maruyama
- Laboratory of Host Defense, IFReC, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yukiko Fujita
- Laboratory of Malaria Immunology, Immunology Frontier Research Center (IFReC), Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Aki Konishi
- Laboratory of Malaria Immunology, Immunology Frontier Research Center (IFReC), Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Patrick M Lelliott
- Laboratory of Malaria Immunology, Immunology Frontier Research Center (IFReC), Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Sawako Itagaki
- Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Toshihiro Horii
- Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Jing-Wen Lin
- Leiden Malaria Research Group, Department of Parasitology, Leiden University Medical Centre, 2333 ZA Leiden, Netherlands.,Division of Pediatric Infectious Diseases, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University and Collaboration Innovation Centre, Chengdu 610041, China
| | - Shahid M Khan
- Leiden Malaria Research Group, Department of Parasitology, Leiden University Medical Centre, 2333 ZA Leiden, Netherlands
| | - Etsushi Kuroda
- Laboratory of Vaccine Science, IFReC, Osaka University, Suita, Osaka 565-0871, Japan.,Laboratory of Adjuvant Innovation, National Institutes of Biomedical Innovation, Health and Nutrition, 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Shizuo Akira
- Laboratory of Host Defense, IFReC, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ken J Ishii
- Laboratory of Vaccine Science, IFReC, Osaka University, Suita, Osaka 565-0871, Japan.,Laboratory of Adjuvant Innovation, National Institutes of Biomedical Innovation, Health and Nutrition, 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Cevayir Coban
- Laboratory of Malaria Immunology, Immunology Frontier Research Center (IFReC), Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Burgess S, Thompson SG. Interpreting findings from Mendelian randomization using the MR-Egger method. Eur J Epidemiol 2017; 32:377-389. [PMID: 28527048 PMCID: PMC5506233 DOI: 10.1007/s10654-017-0255-x] [Citation(s) in RCA: 1608] [Impact Index Per Article: 229.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 05/07/2017] [Indexed: 12/11/2022]
Abstract
Mendelian randomization-Egger (MR-Egger) is an analysis method for Mendelian randomization using summarized genetic data. MR-Egger consists of three parts: (1) a test for directional pleiotropy, (2) a test for a causal effect, and (3) an estimate of the causal effect. While conventional analysis methods for Mendelian randomization assume that all genetic variants satisfy the instrumental variable assumptions, the MR-Egger method is able to assess whether genetic variants have pleiotropic effects on the outcome that differ on average from zero (directional pleiotropy), as well as to provide a consistent estimate of the causal effect, under a weaker assumption-the InSIDE (INstrument Strength Independent of Direct Effect) assumption. In this paper, we provide a critical assessment of the MR-Egger method with regard to its implementation and interpretation. While the MR-Egger method is a worthwhile sensitivity analysis for detecting violations of the instrumental variable assumptions, there are several reasons why causal estimates from the MR-Egger method may be biased and have inflated Type 1 error rates in practice, including violations of the InSIDE assumption and the influence of outlying variants. The issues raised in this paper have potentially serious consequences for causal inferences from the MR-Egger approach. We give examples of scenarios in which the estimates from conventional Mendelian randomization methods and MR-Egger differ, and discuss how to interpret findings in such cases.
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Affiliation(s)
- Stephen Burgess
- MRC Biostatistics Unit, Cambridge Institute of Public Health, University of Cambridge, Forvie Site, Robinson Way, Cambridge, CB2 0SR, UK.
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK.
| | - Simon G Thompson
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK
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Wang L, Robins JM, Richardson TS. On falsification of the binary instrumental variable model. Biometrika 2017; 104:229-236. [PMID: 29505035 PMCID: PMC5819759 DOI: 10.1093/biomet/asw064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Indexed: 01/16/2023] Open
Abstract
Instrumental variables are widely used for estimating causal effects in the presence of
unmeasured confounding. The discrete instrumental variable model has testable implications
for the law of the observed data. However, current assessments of instrumental validity
are typically based solely on subject-matter arguments rather than these testable
implications, partly due to a lack of formal statistical tests with known properties. In
this paper, we develop simple procedures for testing the binary instrumental variable
model. Our methods are based on existing techniques for comparing two treatments, such as
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}{}$t$\end{document}-test and the Gail–Simon test. We illustrate
the importance of testing the instrumental variable model by evaluating the exogeneity of
college proximity using the National Longitudinal Survey of Young Men.
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Affiliation(s)
- Linbo Wang
- Department of Biostatistics, Harvard School of Public Health, 677 Huntington Avenue, Boston, Massachusetts 02115, U.S.A
- Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, Massachusetts 02115,
- Department of Statistics, University of Washington, Box 354322, Washington 98195,
| | - James M Robins
- Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, Massachusetts 02115,
- Department of Statistics, University of Washington, Box 354322, Washington 98195,
| | - Thomas S Richardson
- Department of Statistics, University of Washington, Box 354322, Washington 98195,
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Abstract
Rationale: Several studies have demonstrated links between infectious diseases and cardiovascular conditions. Malaria and hypertension are widespread in many low- and middle-income countries, but the possible link between them has not been considered. Objective: In this article, we outline the basis for a possible link between malaria and hypertension and discuss how the hypothesis could be confirmed or refuted. Methods and Results: We reviewed published literature on factors associated with hypertension and checked whether any of these were also associated with malaria. We then considered various study designs that could be used to test the hypothesis. Malaria causes low birth weight, malnutrition, and inflammation, all of which are associated with hypertension in high-income countries. The hypothetical link between malaria and hypertension can be tested through the use of ecological, cohort, or Mendelian randomization studies, each of which poses specific challenges. Conclusions: Confirmation of the existence of a causative link with malaria would be a paradigm shift in efforts to prevent and control hypertension and would stimulate wider research on the links between infectious and noncommunicable disease.
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Affiliation(s)
- Anthony O Etyang
- From the Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya (A.O.E., J.A.G.S.); Department of Infectious Disease Epidemiology (A.O.E., J.A.G.S.), and Department of Non-Communicable Disease Epidemiology (L.S.), London School of Hygiene and Tropical Medicine, London, United Kingdom; and Cardiovascular Medicine Group, Division of Diabetes and Nutritional Sciences, King's College, London, United Kingdom (J.K.C.).
| | - Liam Smeeth
- From the Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya (A.O.E., J.A.G.S.); Department of Infectious Disease Epidemiology (A.O.E., J.A.G.S.), and Department of Non-Communicable Disease Epidemiology (L.S.), London School of Hygiene and Tropical Medicine, London, United Kingdom; and Cardiovascular Medicine Group, Division of Diabetes and Nutritional Sciences, King's College, London, United Kingdom (J.K.C.)
| | - J Kennedy Cruickshank
- From the Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya (A.O.E., J.A.G.S.); Department of Infectious Disease Epidemiology (A.O.E., J.A.G.S.), and Department of Non-Communicable Disease Epidemiology (L.S.), London School of Hygiene and Tropical Medicine, London, United Kingdom; and Cardiovascular Medicine Group, Division of Diabetes and Nutritional Sciences, King's College, London, United Kingdom (J.K.C.)
| | - J Anthony G Scott
- From the Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya (A.O.E., J.A.G.S.); Department of Infectious Disease Epidemiology (A.O.E., J.A.G.S.), and Department of Non-Communicable Disease Epidemiology (L.S.), London School of Hygiene and Tropical Medicine, London, United Kingdom; and Cardiovascular Medicine Group, Division of Diabetes and Nutritional Sciences, King's College, London, United Kingdom (J.K.C.)
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Monteiro WM, Alexandre MA, Siqueira A, Melo G, Romero GAS, d'Ávila E, Benzecry SG, Leite HP, Lacerda MVG. Could Plasmodium vivax malaria trigger malnutrition? Revisiting the Bradford Hill criteria to assess a causal relationship between two neglected problems. Rev Soc Bras Med Trop 2016; 49:274-8. [PMID: 27384822 DOI: 10.1590/0037-8682-0397-2015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 04/13/2016] [Indexed: 02/02/2023] Open
Abstract
The benign characteristics formerly attributed to Plasmodium vivax infections have recently changed owing to the increasing number of reports of severe vivax malaria resulting in a broad spectrum of clinical complications, probably including undernutrition. Causal inference is a complex process, and arriving at a tentative inference of the causal or non-causal nature of an association is a subjective process limited by the existing evidence. Applying classical epidemiology principles, such as the Bradford Hill criteria, may help foster an understanding of causality and lead to appropriate interventions being proposed that may improve quality of life and decrease morbidity in neglected populations. Here, we examined these criteria in the context of the available data suggesting that vivax malaria may substantially contribute to childhood malnutrition. We found the data supported a role for P. vivax in the etiology of undernutrition in endemic areas. Thus, the application of modern causal inference tools, in future studies, may be useful in determining causation.
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Affiliation(s)
- Wuelton Marcelo Monteiro
- Diretoria de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brasil.,Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Amazonas, Brasil
| | - Márcia Araújo Alexandre
- Diretoria de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brasil.,Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Amazonas, Brasil
| | - André Siqueira
- Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brasil
| | - Gisely Melo
- Diretoria de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brasil.,Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Amazonas, Brasil
| | | | - Efrem d'Ávila
- Diretoria de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brasil.,Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Amazonas, Brasil
| | - Silvana Gomes Benzecry
- Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Amazonas, Brasil.,Departamento de Pediatria, Universidade Federal de São Paulo, São Paulo, São Paulo, Brasil
| | - Heitor Pons Leite
- Departamento de Pediatria, Universidade Federal de São Paulo, São Paulo, São Paulo, Brasil
| | - Marcus Vinícius Guimarães Lacerda
- Diretoria de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brasil.,Instituto de Pesquisa Leônidas & Maria Deane, Fundação Oswaldo Cruz, Manaus, Amazonas, Brasil
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Mosites E, Thumbi SM, Otiang E, McElwain TF, Njenga MK, Rabinowitz PM, Rowhani-Rahbar A, Neuhouser ML, May S, Palmer GH, Walson JL. Relations between Household Livestock Ownership, Livestock Disease, and Young Child Growth. J Nutr 2016; 146:1118-24. [PMID: 27075911 PMCID: PMC4841921 DOI: 10.3945/jn.115.225961] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 03/07/2016] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND In resource-limited settings in which child malnutrition is prevalent, humans live in close proximity to household livestock. However, the relation between household livestock and child nutrition represents a considerable knowledge gap. OBJECTIVE We assessed whether household livestock ownership or livestock disease episodes were associated with growth in young children in western Kenya. METHODS We incorporated monthly anthropometric measurements for children <5 y of age into an ongoing linked human and animal surveillance cohort in rural western Kenya. Using linear mixed models adjusted for age, sex, and household wealth, we tested whether baseline household livestock ownership was related to baseline child height for age or prospective growth rate. We also evaluated whether livestock disease episodes were associated with child growth rate over 11 mo of follow-up. RESULTS We collected data on 925 children over the course of follow-up. Greater household livestock ownership at baseline was not related to baseline child height-for-age z score (adjusted β: 0.01 SD; 95% CI: -0.02, 0.04 SD) or child growth rate (adjusted β: 0.02 cm/y; 95% CI: -0.03, 0.07 cm/y). Livestock disease episodes were not significantly associated with child growth across the entire cohort (adjusted β: -0.007 cm/mo; 95% CI: -0.02, 0.006 cm/mo). However, children in households with livestock digestive disease between June and November gained less height than did children in households that did not report livestock disease (β: -0.063 cm/mo; 95% CI: -0.112, -0.016 cm/mo). Children <2 y of age in households with livestock digestive disease gained less weight than did those who did not report disease (β: -0.033 kg/mo; 95% CI: -0.063, -0.003 kg/mo). CONCLUSION In this cohort of young children in western Kenya, we did not find an association between ownership of livestock and child growth status. However, disease episodes in household livestock may be related to a lower child growth rate in some groups.
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Affiliation(s)
- Emily Mosites
- Department of Epidemiology, Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA;
| | - Samuel M Thumbi
- Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA
| | | | - Terry F McElwain
- Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA
| | - MK Njenga
- Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA
| | | | | | - Marian L Neuhouser
- Department of Epidemiology,,Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA
| | | | - Guy H Palmer
- Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA
| | - Judd L Walson
- Department of Epidemiology,,Department of Global Health,,Department of Medicine,,Department of Pediatrics, University of Washington, Seattle, WA
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Kang H, Kreuels B, May J, Small DS. Full matching approach to instrumental variables estimation with application to the effect of malaria on stunting. Ann Appl Stat 2016. [DOI: 10.1214/15-aoas894] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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40
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Ferreira ED, Alexandre MA, Salinas JL, de Siqueira AM, Benzecry SG, de Lacerda MVG, Monteiro WM. Association between anthropometry-based nutritional status and malaria: a systematic review of observational studies. Malar J 2015; 14:346. [PMID: 26377094 PMCID: PMC4574180 DOI: 10.1186/s12936-015-0870-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/25/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Multiple studies in various parts of the world have analysed the association of nutritional status on malaria using anthropometric measures, but results differ due to the heterogeneity of the study population, species of the parasite, and other factors involved in the host and parasite relationship. The aim of this study was to perform a systematic review on the inter-relationship of nutritional status based on anthropometry and malarial infection. METHODS Two independent reviewers accessed the MEDLINE and LILACS databases using the same search terms related to malaria and anthropometry. Prospective studies associating anthropometry and malaria (incidence or severity) were selected. References from the included studies and reviews were used to increase the review sensitivity. Data were extracted using a standardized form and the quality of the prospective studies was assessed. Selected articles were grouped based on exposures and outcomes. RESULTS The search identified a total of 1688 studies: 1629 from MEDLINE and 59 from LILACS. A total of 23 met the inclusion criteria. Five additional studies were detected by reading the references of the 23 included studies and reviews, totaling 28 studies included. The mean sample size was 662.1 people, ranging from 57 to 5620. The mean follow-up was 365.8 days, ranging from 14 days to 1 year and 9 months, and nine studies did not report the follow-up period. Prospective studies assessing the relationship between malaria and malnutrition were mostly carried out in Africa. Of the 20 studies with malarial outcomes, fifteen had high and five had average quality, with an average score of 80.5 %. Most anthropometric parameters had no association with malaria incidence (47/52; 90.4 %) or parasite density (20/25; 80 %). However, the impact of malnutrition was noted in malaria mortality and severity (7/17; 41.2 %). Regarding the effects of malaria on malnutrition, malaria was associated with very few anthropometric parameters (8/39; 20.6 %). CONCLUSIONS This systematic review found that most of the evidence associating malaria and malnutrition comes from P. falciparum endemic areas, with a significant heterogeneity in studies' design. Apparently malnutrition has not a great impact on malaria morbidity, but could have a negative impact on malaria mortality and severity. Most studies show no association between malaria and subsequent malnutrition in P. falciparum areas. In Plasmodium vivax endemic areas, malaria was associated with malnutrition in children. A discussion among experts in the field is needed to standardize future studies to increase external validity and accuracy.
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Affiliation(s)
- Efrem d'Avila Ferreira
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Universidade do Estado do Amazonas, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
| | - Márcia A Alexandre
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Universidade do Estado do Amazonas, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
| | - Jorge L Salinas
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, 49 Jesse Hill Jr Drive, Atlanta, GA, 30303, USA.
| | - André M de Siqueira
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Universidade do Estado do Amazonas, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz, Av. Brasil, 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil.
| | - Silvana G Benzecry
- Universidade do Estado do Amazonas, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
| | - Marcus V G de Lacerda
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Universidade do Estado do Amazonas, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Instituto de Pesquisas Leônidas and Maria Deane, Fundação Oswaldo Cruz, Rua Terezina, 476, Adrianópolis, Manaus, AM, 69057-070, Brazil.
| | - Wuelton M Monteiro
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Universidade do Estado do Amazonas, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
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Burgess S, Timpson NJ, Ebrahim S, Davey Smith G. Mendelian randomization: where are we now and where are we going? Int J Epidemiol 2015; 44:379-88. [DOI: 10.1093/ije/dyv108] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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42
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Boef AGC, Dekkers OM, le Cessie S. Mendelian randomization studies: a review of the approaches used and the quality of reporting. Int J Epidemiol 2015; 44:496-511. [PMID: 25953784 DOI: 10.1093/ije/dyv071] [Citation(s) in RCA: 244] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Mendelian randomization (MR) studies investigate the effect of genetic variation in levels of an exposure on an outcome, thereby using genetic variation as an instrumental variable (IV). We provide a meta-epidemiological overview of the methodological approaches used in MR studies, and evaluate the discussion of MR assumptions and reporting of statistical methods. METHODS We searched PubMed, Medline, Embase and Web of Science for MR studies up to December 2013. We assessed (i) the MR approach used; (ii) whether the plausibility of MR assumptions was discussed; and (iii) whether the statistical methods used were reported adequately. RESULTS Of 99 studies using data from one study population, 32 used genetic information as a proxy for the exposure without further estimation, 44 performed a formal IV analysis, 7 compared the observed with the expected genotype-outcome association, and 1 used both the latter two approaches. The 80 studies using data from multiple study populations used many different approaches to combine the data; 52 of these studies used some form of IV analysis; 44% of studies discussed the plausibility of all three MR assumptions in their study. Statistical methods used for IV analysis were insufficiently described in 14% of studies. CONCLUSIONS Most MR studies either use the genotype as a proxy for exposure without further estimation or perform an IV analysis. The discussion of underlying assumptions and reporting of statistical methods for IV analysis are frequently insufficient. Studies using data from multiple study populations are further complicated by the combination of data or estimates. We provide a checklist for the reporting of MR studies.
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Affiliation(s)
- Anna G C Boef
- Department of Clinical Epidemiology, Department of Endocrinology and Metabolic Diseases, and Department of Medical Statistics and Bioinformatics, Leiden University Medical Centre, Leiden, The Netherlands.
| | - Olaf M Dekkers
- Department of Clinical Epidemiology, Department of Endocrinology and Metabolic Diseases, and Department of Medical Statistics and Bioinformatics, Leiden University Medical Centre, Leiden, The Netherlands. Department of Clinical Epidemiology, Department of Endocrinology and Metabolic Diseases, and Department of Medical Statistics and Bioinformatics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Saskia le Cessie
- Department of Clinical Epidemiology, Department of Endocrinology and Metabolic Diseases, and Department of Medical Statistics and Bioinformatics, Leiden University Medical Centre, Leiden, The Netherlands. Department of Clinical Epidemiology, Department of Endocrinology and Metabolic Diseases, and Department of Medical Statistics and Bioinformatics, Leiden University Medical Centre, Leiden, The Netherlands
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Hess SY, Abbeddou S, Jimenez EY, Somé JW, Vosti SA, Ouédraogo ZP, Guissou RM, Ouédraogo JB, Brown KH. Small-quantity lipid-based nutrient supplements, regardless of their zinc content, increase growth and reduce the prevalence of stunting and wasting in young burkinabe children: a cluster-randomized trial. PLoS One 2015; 10:e0122242. [PMID: 25816354 PMCID: PMC4376671 DOI: 10.1371/journal.pone.0122242] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 02/12/2015] [Indexed: 02/05/2023] Open
Abstract
UNLABELLED Small-quantity lipid-based nutrient supplements (SQ-LNS) are promising home fortification products, but the optimal zinc level needed to improve growth and reduce morbidity is uncertain. We aimed to assess the impact of providing SQ-LNS with varied amounts of zinc, along with illness treatment, on zinc-related outcomes compared with standard care. In a placebo-controlled, cluster-randomized trial, 34 communities were stratified to intervention (IC) or non-intervention cohorts (NIC). 2435 eligible IC children were randomly assigned to one of four groups:1) SQ-LNS without zinc, placebo tablet; 2) SQ-LNS containing 5mg zinc, placebo tablet; 3) SQ-LNS containing 10mg zinc, placebo tablet; or 4) SQ-LNS without zinc and 5mg zinc tablet from 9–18 months of age. During weekly morbidity surveillance, oral rehydration salts were provided for reported diarrhea and antimalarial therapy for confirmed malaria. Children in NIC (n = 785) did not receive SQ-LNS, tablets, illness surveillance or treatment. At 9 and 18 months, length, weight and hemoglobin were measured in all children. Reported adherence was 97 ± 6% for SQ-LNS and tablets. Mean baseline hemoglobin was 89 ± 15g/L. At 18 months, change in hemoglobin was greater in IC than NIC (+8 vs -1g/L, p<0.0001), but 79.1% of IC were still anemic (vs. 91.1% in NIC). Final plasma zinc concentration did not differ by group. During the 9-month observation period, the incidence of diarrhea was 1.10 ± 1.03 and of malaria 0.54 ± 0.50 episodes per 100 child-days, and did not differ by group. Length at 18 months was significantly greater in IC compared to NIC (77.7 ± 3.0 vs. 76.9 ± 3.4 cm; p<0.001) and stunting prevalence was significantly lower in IC (29.3%) than NIC (39.3%; p<0.0001), but did not differ by intervention group within IC. Wasting prevalence was also significantly lower in IC (8.7%) than in NIC (13.5%; p = 0.0003). Providing SQ-LNS daily with or without zinc, along with malaria and diarrhea treatment, significantly increased growth and reduced stunting, wasting and anemia prevalence in young children. TRIAL REGISTRATION ClinicalTrials.gov NCT00944281.
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Affiliation(s)
- Sonja Y. Hess
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
| | - Souheila Abbeddou
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
| | - Elizabeth Yakes Jimenez
- Nutrition Program, Department of Individual, Family and Community Education, University of New Mexico, Albuquerque, NM, United States of America
| | - Jérôme W. Somé
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Stephen A. Vosti
- Agricultural and Resource Economics, University of California Davis, Davis, CA, United States of America
| | | | | | | | - Kenneth H. Brown
- Program in International and Community Nutrition, Department of Nutrition, University of California Davis, Davis, CA, United States of America
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Baiocchi M, Cheng J, Small DS. Instrumental variable methods for causal inference. Stat Med 2014; 33:2297-340. [PMID: 24599889 PMCID: PMC4201653 DOI: 10.1002/sim.6128] [Citation(s) in RCA: 357] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 01/24/2014] [Accepted: 02/10/2014] [Indexed: 01/03/2023]
Abstract
A goal of many health studies is to determine the causal effect of a treatment or intervention on health outcomes. Often, it is not ethically or practically possible to conduct a perfectly randomized experiment, and instead, an observational study must be used. A major challenge to the validity of observational studies is the possibility of unmeasured confounding (i.e., unmeasured ways in which the treatment and control groups differ before treatment administration, which also affect the outcome). Instrumental variables analysis is a method for controlling for unmeasured confounding. This type of analysis requires the measurement of a valid instrumental variable, which is a variable that (i) is independent of the unmeasured confounding; (ii) affects the treatment; and (iii) affects the outcome only indirectly through its effect on the treatment. This tutorial discusses the types of causal effects that can be estimated by instrumental variables analysis; the assumptions needed for instrumental variables analysis to provide valid estimates of causal effects and sensitivity analysis for those assumptions; methods of estimation of causal effects using instrumental variables; and sources of instrumental variables in health studies.
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Affiliation(s)
- Michael Baiocchi
- Department of Statistics, Stanford University, Stanford, CA, U.S.A
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Abstract
Linear growth failure is the most common form of undernutrition globally. With an estimated 165 million children below 5 years of age affected, stunting has been identified as a major public health priority, and there are ambitious targets to reduce the prevalence of stunting by 40% between 2010 and 2025. We view this condition as a 'stunting syndrome' in which multiple pathological changes marked by linear growth retardation in early life are associated with increased morbidity and mortality, reduced physical, neurodevelopmental and economic capacity and an elevated risk of metabolic disease into adulthood. Stunting is a cyclical process because women who were themselves stunted in childhood tend to have stunted offspring, creating an intergenerational cycle of poverty and reduced human capital that is difficult to break. In this review, the mechanisms underlying linear growth failure at different ages are described, the short-, medium- and long-term consequences of stunting are discussed, and the evidence for windows of opportunity during the life cycle to target interventions at the stunting syndrome are evaluated.
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Affiliation(s)
- Andrew J Prendergast
- Centre for Paediatrics, Blizard Institute, Queen Mary University of London, UK,Zvitambo Institute for Maternal and Child Health Research, Harare, Zimbabwe,Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Jean H Humphrey
- Zvitambo Institute for Maternal and Child Health Research, Harare, Zimbabwe,Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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46
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Ferrie JE. On the cause of offence. Int J Epidemiol 2013. [DOI: 10.1093/ije/dyt206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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